That would ROCK IMO!
But why use D20 system when you shoot? At the beginning, you have a huge croshair.
You gain more strength and feats, your croshair gets smaller, thus the weaps more accurate...
And no need t change the melee. The melee fighting animations are simply great!!!

*Note: Chapter 8 is out!*
[Fic] The war of the ancients, seen through the eyes of one young men, as he walks the road of destiny... The Triumvirates War